Catastrophic Case Report
(Acute Abdomen-Failure to Rescue)
Synopsis
∙ Patient with “Rigid Abdomen”
∙ Negative –plain X-ray
∙ “Watchful waiting”-delayed CT
∙ Death from Perforated Small Bowel
8 month old child:
∙ Temp 40.3°C . . . HR 199
A∙Report
from
the FH Patient Safety Review Committee
Looks
well
∙ No Treatment, discharged
∙ Sudden Death 48 hours later
Report Prepared: Date
CONFIDENTIAL for Quality Improvement Purposes only.
ACUTE ABDOMEN-PERFORATED VISCUS-THE ROLE OF CT AND ANTIBIOTIC CHOICE
Executive Summary-Briefing
Case Summary
A patient was sent to the ER with presumptive diagnosis of “Perforated Viscus.” The patient had a board-like
abdomen and elevated WBC with severe pain. Abdominal plain films were normal and were repeated after the
gastric insufflation of 500cc air by an NG tube. A second set of films was also negative. The patient was
admitted overnight for observation and prescribed Morphine, Cefazolin and Metronidazole. During the night
there was progressive development of sepsis. The patient had a CT scan of the abdomen the following
morning. This demonstrated a small amount of free intraperitoneal air and thickening of the mid small bowel
wall. The patient was taken to the OR and died immediately after resection of a perforated segment of small
bowel. Pathology revealed a small bowel lymphoma with perforation. Cause of death was sepsis secondary to
bowel perforation and peritonitis.
Background
The ‘Acute abdomen’ is a general term applied to patients presenting with severe, acute abdominal pain. In
these cases, the examining physician searches for the etiology with some urgency as they often require
surgical intervention. The clinician "makes a serious and thorough attempt at diagnosis by means of the
history, physical examination and ancillary diagnostics."
Two concerns stood out in the review.
Why was an abdominal CT not performed when plain films were negative?
Why was Cefazolin/Flagyl chosen as antibiotic coverage?
This patient presented with a “Rigid Abdomen” and early surgical intervention was
likely the preferred approach. Diagnostic Laparotomy is a valuable tool. In Surgical
practice delays for diagnostic work ups should be weighed against the risk of
catastrophic septic complications in the Acute abdomen.
CT SCAN IN ACUTE ABDOMEN
CT has become the front line diagnostic tool to aid history and physical exam in the evaluation the acute
abdomen. Despite good clinical skills, there are times and circumstances where CT is essential in the
disposition and management of a patient. This is especially true when the clinical presentation is confusing. In
some cases of acute appendicitis or diverticulitis with abscess formation, the accurate diagnosis of the
problem can lead to non-operative image-guided, percutaneous therapy. In free perforations (as in this case),
ischemic bowel or a closed loop small bowel obstruction, the rapid diagnosis by CT may facilitate surgery.
Plain abdominal films have limited utility (may reveal ileus, bowel obstruction, free
air, ascites or interstitial gas. CT has supplanted plain films in the Acute Abdomen.
The advantages of CT include versatility and a wide margin of error. It provides a
global survey of the abdomen, presents useful surgical anatomy and has high
sensitivity in detecting pneumoperitoneum
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Page A
ANTIBIOTIC CHOICES FOR INTRA-ABDOMINAL INFECTIONS (possible perforated viscus)
This patient was given a standard cocktail of Cefazolin and Flagyl for possible perforated viscus. A random
survey of Emergency Physicians, Surgeons and Internists revealed a variable approach to empiric treatment
of “Acute Abdomen”. A review of the literature and consultation with local experts has facilitated development
of the following guideline to antibiotic choices in Intra-abdominal infections.
Background
Intra-abdominal infection is often triggered by GI perforation leakage of gastrointestinal contents with
development of generalized peritonitis or abscess in the abdominal cavity. The majority of intra-abdominal
infections are characteristically ‘secondary bacterial peritonitis.’ Hollow viscus perforation accounts for 60-80%
of all reported cases of secondary peritonitis. Surgical intervention is often required expeditiously to improve
patient outcomes.
Summary
Antibiotic regimens for intraabdominal infections based on FHA Formulary
Low-risk patients
Antibiotic Regimen (average doses listed)a
Cefazolin 1 g IV Q8H
Or Cefuroxime 750 mg IV Q8H
Plus Metronidazole 500 mg IV Q8-12H
Gentamicin 2.5 mg/Kg mg IV Q8Ha
Plus Metronidazole 500 mg IV Q8-121H
Or Clindamycin 600 mg IV Q8H b
High-risk patients
(always consider
confounding factors
such as immune status,
sepsis, etc.)
Drug cost per day
$11.22
$8.85
$3.66
$8.31
$7.14
$3.66
Ertapenem 1g IV Q24H
$49.95
Ticarcillin/Clavulinate 3.1g IV Q6H
Cetriaxone 1 g IV Q24H
Plus Metronidazole 500 mg IV Q8-12H
$38.44
$34.00
$3.66
Gentamicin 2.5 mg/Kg mg IV Q8Ha
Plus Metronidazole 500 mg IV Q8-12H
Or Clindamycin 600 mg IV Q8H b
(+/- Ampicillin 1G IV Q6H)
$8.31
$7.14
$3.66
$3.00
Ciprofloxacin 400 mg IV Q12Hc
Plus Metronidazole 500 mg IV Q8-12H
$66.00
$3.66
Piperacillin/tazobactam 3.375 mg IV Q6H
$62.28
Imipenem/cilastatin or Meropenem
500 mg IV Q6H
$97.52
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Page B
Catastrophic Case Report
Acute Abdomen: Diagnostic Imaging and Antibiotic Choices
Brian McGowan, MD; Lily Cheng, PharmD
The ‘acute abdomen’ is a general term applied to any patient presenting with severe, acute abdominal pain. In
these cases, the examining physician searches for the etiology with some urgency, as these patients often
require either hospital admission and/or surgical intervention. Evaluation of these patients starts with "making
a serious and thorough attempt at diagnosis, usually predominantly by means of the history and physical
examination."
A recent FH case illustrates some of the difficulties encountered in managing these cases.
CASE REPORT
A patient was sent to the ER by a clinic physician with presumptive diagnosis of “Perforated Viscus.” The
patient had a board-like abdomen severe pain and elevated WBC. Abdominal plain films were normal and
were repeated after the gastric insufflation of 500cc air by an NG tube. The second set of films was also
negative at about midnight. The patient was admitted for observation and prescribed Morphine, Cefazolin and
Metronidazole. During the night there was progressive development of sepsis. The patient had a CT scan of
the abdomen the following morning. This demonstrated a small amount of free intraperitoneal air and
thickening of the mid small bowel wall. The patient was taken to the OR and died immediately after resection
of a perforated segment of small bowel was removed. Pathology revealed a small bowel lymphoma with
perforation. Cause of death was sepsis secondary to bowel perforation and peritonitis.
CASE REVIEW
Two concerns stood out in the review. Why was an abdominal CT not performed when plain films were
negative? Why was Cefazolin/Flagyl chosen as antibiotic coverage?
These questions will be looked at separately but should not take away from the dominant concern. This
patient presented with a “Rigid Abdomen” and early surgical intervention was likely the preferred approach.
Diagnostic Laparotomy is a very valuable tool in the General Surgeons practice and watchful waiting or
protracted delays for diagnostic work up should not delayed needed Surgery.
“Rigid Abdomen” - early surgical intervention was likely the preferred approach.”
CT SCAN IN ACUTE ABDOMEN
CT has become the front line diagnostic tool to aid history and physical exam in the evaluation the acute
abdomen. Despite good clinical skills, there are times and circumstances where CT is essential in the
disposition and management of a patient. This is especially true when the clinical presentation is confusing. In
some cases of acute appendicitis or diverticulitis with abscess formation, the accurate diagnosis of the
problem can lead to non-operative, image-guided, percutaneous therapy. In small perforations (as in this
case), ischemic bowel or a closed loop small bowel obstruction, the rapid diagnosis by CT may
facilitate surgery.
CONFIDENTIAL for Quality Improvement Purposes only.
Page C
CT TECHNIQUES IN THE ACUTE ABDOMEN
Plain abdominal films have limited utility but can reveal the presence of an ileus or bowel obstruction, free
intraperitoneal air, ascites and interstitial gas. CT is supplanting plain films as the imaging procedure of choice
in the Acute Abdomen. The advantages of CT include versatility and a wide margin of error. It provides a
global survey of the abdomen, presents useful surgical anatomy and detects pneumoperitoneum.
There are five possible CT techniques in the evaluation of a patient with an acute abdomen: Plain CT; IV
contrast; Oral and IV contrast; Rectal and IV contrast; Oral, rectal and IV contrast.
Plain CT is the fastest, but most limited of the techniques. Some radiologists use this technique very
effectively. It is important to at least have a working Differential Diagnosis in the patient evaluated for acute
abdominal pain.
The ideal strategy for CT in the acute abdomen is IV and oral contrast (occasionally with rectal contrast). With
this technique, blood vessels and the bowel are opacified, extravasation is identified, abnormal enhancement
can be detected (less inherent body contrast (fat) is useful for delineating margins). This technique can be
time consuming and the patient must be cooperative with reasonable renal function and there can be contrast
media reactions.
IV contrast alone is convenient but with thin patients, bowel details are limited as fat is relatively absent.
Rectal contrast alone yields a focused exam and is effective in diagnosing colonic disorders such as
diverticulitis and appendicitis, but limits evaluation of the remainder of the exam.
CT-THE ACUTE ABDOMEN: COMMON DIAGNOSIS
Appendicitis
In most patients, especially in men, the clinical diagnosis of acute appendicitis is straightforward and does not
necessarily require imaging confirmation unless the presentation is atypical. In patients with a confusing
clinical picture, especially in the aged and females, the diagnosis can be very difficult. The differential
diagnosis of findings in the right lower quadrant is important and includes, right sided diverticulitis, renal colic,
PID, infectious or inflammatory disease and carcinoma of the Cecum or Appendix. Asians have a higher
incidence of right-sided diverticulitis.
In an early retrospective study of 100 patients with atypical or non-specific clinical presentation, the sensitivity
and specificity was 98% and 83% respectively. A diseased appendix was present in 45/50 and appendicoliths
in 17/60 (an appendicolith is diagnostic).
Recent studies have noted an increased incidence in perforations and complications when patients are
required to have a CT scan prior to Appendectomy. The CT diagnosis of acute appendicitis is based upon
detecting one or two positive findings. The abnormal appendix is visualized as a distended, fluid-filled, thickwalled tubular shaped structure located to the right of the midline from the subhepatic space to the pelvis. It is
often associated with soft tissue changes in the peri-cecal fat.
CT studies have confirmed that some cases of acute appendicitis can resolve with conservative treatment.
Smouldering acute appendicitis or missed acute appendicitis with rupture can have the appearance of a
tumour. It is also important to note that CT can guide management in patients with complicated appendicitis.
In one four-year study of 70 patients with suspected peri-appendiceal inflammatory masses, three
management groups were created. Those patients with a peri-appendiceal phlegmon of small abscesses
were initially treated with antibiotics alone. Those with well-defined peri-appendiceal abscesses were treated
with CT guided percutaneous catheter drainage with complete resolution in almost all. Lastly, those patients
presenting with multilocular/ multi-compartmental abscesses were immediately explored and drained.
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Page D
Bowel Obstruction
Plain films of the abdomen detect small bowel obstruction in about 60-70% of cases. Differentiating ileus from
incomplete or subacute bowel obstruction can be extremely difficult.
The CT findings of a small bowel obstruction include the presence of small bowel dilatation (a lumen of
greater than 2.5 cm) and the presence of a transition point (e.g. collapsed distal bowel). In one series, there
was about 95% sensitivity and specificity in the diagnosis of a small bowel obstruction. About 50% of patients
with a strangulating obstruction are not clinically diagnosed pre-operatively. CT findings of a closed-loop and
strangulating intestinal obstruction are helpful in many of these cases.
When a small bowel obstruction is present, ischemic changes of the small bowel can occur even without
strangulation or entrapment. In one study of patients with this type of ischemic bowel there were no false
negative CT diagnoses but there were 12 false positives (specificity was 61%). CT is highly sensitive but not
as specific.
Acute Diverticulitis
CT has become the imaging procedure of choice in the diagnosis and management of patients with acute
diverticulitis. Recent studies have demonstrated CT sensitivity of 97% and a specificity of 100%. Importantly,
alternative diagnoses are often identified on CT in over half of the patients thought to have diverticulitis pre
scan. Ultrasound has about 85% sensitivity and specificity.
The CT typically reveals wall thickening, peri-colic fat changes and abscess formation. Other findings include
fistulae, bowel or ureteric obstruction and peritonitis. Localized abscess formation is seen in 35-50% of
patients. If an abscess is detected, it is common practice to percutaneously treat if technically feasible. The
objective is percutaneous resolution of the abscess so the patient will avoid surgery.
Other Causes of Acute Abdominal Pain Detected on CT
Ischemic bowel is a common cause of acute abdominal pain in the aged vasculopath patient. No imaging
procedure is reliable for these cases but CT is probably the imaging procedure of choice. Unfortunately CT is
limited because the most common findings: bowel dilatation, thickening of the bowel wall and a negative scan
do not exclude the diagnosis of ischemic bowel.
With the increasing use of CT in the evaluation of any patient with acute abdominal pain, there are a number
of findings unexpectedly detected. A perforated duodenal ulcer is not uncommonly diagnosed on a CT.
Most of these patients have a pneumoperitoneum as well as soft tissue changes adjacent to the stomach
and/or duodenum.
Acute cholecystitis is also found on CT. Patients are usually sent to CT because of confusing findings
including non-localized right-sided abdominal pain. The query in these cases is acute appendicitis vs. acute
cholecystitis or some other cause.
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Page E
ROLE OF CT IN THE EVALUATION OF THE ACUTE ABDOMEN
In one review of 40 admitted patients with “Acute Abdominal pain NYD”, CT showed intestinal obstruction
in about 40%. Other CT diagnosis included peritonitis, inflammatory bowel disease, diverticulitis, mesenteric
ischemia, pancreatitis, cholecystitis and hemo-peritoneum. The pre-CT clinical diagnosis was correct 17.5% of
the time while the post-CT diagnosis was accurate 60% of the time.
In another retrospective study, 91 patients admitted with acute abdominal pain and initially treated
conservatively were scanned because of a failed response to initial conservative therapy. Most of these
patients were evaluated within 24 hours. Clinical diagnosis was correct in about 60% while CT was correct
85% of the time. CT findings changed therapy in 25 patients; surgery instead of medical therapy was
performed in 15 more cases.
As a final comment to this discussion I asked an FH CT Radiologist to sum up their suggested approach.
They replied:
“In my take of the radiology literature, the consensus is that CT with IV
contrast medium offers the most "bang for the buck". In most cases oral
and rectal contrast medium do not add much more (and are time consuming).
Non IV contrast studies may be fine in people with intra-abdominal fat, but in thin people
the images may be hard to interpret. Of course, any CT is better than
none or just plain radiographs.
In patients with "typical" appendicitis”, the surgeon may choose to take
the patient to OR without a CT scan. Often though, there is enough time
to get CT so that there are no surprises for the surgeon. In children
and young women, US may be the first line imaging, even though not
as sensitive or specific as CT. Of course, one may get a non diagnostic
US and then still need to resort to CT.”
ANTIBIOTIC CHOICES FOR INTRA-ABDOMINAL INFECTIONS (possible perforated viscus)
This patient was given a standard cocktail of Cefazolin and Flagyl for possible perforated viscus. A random
survey of 15 Emergency Physicians, Surgeons and Internists revealed a variable approach to empiric
treatment of “Acute Abdomen”. A review of the literature and consultation with local experts has facilitated
development of the following guideline to antibiotic choices in Intra-abdominal infections.
Background
Intra-abdominal infection is characterized by the presence of gastrointestinal contents or pus in the form of
abscess or generalized peritonitis, in the abdominal cavity. Important differences exist between intraabdominal infection and peritonitis. Peritonitis is classified as primary, secondary and tertiary. Primary
peritonitis is infection without an evident infectious source, whereas secondary peritonitis is caused by leaked
gastrointestinal, genitourinary or other infected fluids in the peritoneal space. Tertiary peritonitis is less welldefined, characterized by persistent or recurrent infections with low virulence organisms and is usually
associated with a systemic inflammatory response syndrome. The majority of intra-abdominal infections are
characteristically ‘secondary bacterial peritonitis.’ They are typically caused by a loss of gastrointestinal wall
integrity secondary to trauma, surgery or intrinsic disease. Hollow viscus perforation accounts for 60-80% of
all reported cases of secondary peritonitis. Surgical intervention is often required expeditiously to improve
patient outcomes.
Microbiology
Antibiotic therapy is dictated by common GI tract micro organisms. Intra-abdominal infections are usually
polymicrobial, involving aerobic and anaerobic enteric organisms. The bacteria isolated depend on the level of
the perforation. The upper GI tract flora has a higher likelihood of gram-positive organisms along with gram-
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Page F
negative organisms; whereas the lower tract flora is mostly gram-negative and anaerobic. Escherichia (E.) coli
is the most commonly encountered enteric aerobe, and Bacteroides (B.) fragilis is the most frequent
anaerobe. (Table 1)
Table 1. Micro organisms isolated from intraabdominal infections
Gram-positive aerobic and facultative
Gram-negative aerobic and facultative
Anaerobic
Micro organisms
Enterococcus sp.
Non-enterococcal Streptococcus sp.
Staphylococcus sp.
Escherichia coli
Enterobacter sp.
Klebsiella sp.
Pseudomonas aeruginosa
Other gram-negative enteric bacilli
Bacteroides fragilis
Other Bacteroides sp.
Clostridium sp.
Peptostreptococcus
Streptococcus
Low-Risk versus High-Risk Infections
Community-acquired intra-abdominal infections are often low-risk infections, (e.g. perforated appendicitis,
diverticulitis). Omental walling and localization of abscess may occur in visceral perforation, causing
“localized” peritoneal irritation. Infections with general peritonitis, SIRS/sepsis, nosocomial infections and
infections in immunocompromized hosts are high risk.
In community-acquired infections, the common aerobic and anaerobic enteric flora are usual, with less
concern about Enterococcus species. Nosocomial infections may involve more resistant gram-negative
organisms, such as Pseudomonas sp., Enterococcus sp, MRSA and Candida sp.
Antibiotic Therapy
The goal of antibiotic therapy is to eradicate infection, prevent recurrent infection, reduce surgical wound
complications and control bacteremia/sepsis. The use of empiric broad-spectrum antimicrobial coverage is
recommended to cover aerobic organisms, facultative Enterbacteriacae and anaerobic organisms, such as B.
fragilis. The Infectious Disease Society of America and the American Surgical Infection Society supports the
use of targeted emperic therapy for the treatment of intra-abdominal infections. (Table 2)
Monotherapy and combination therapy are comparable in efficacy. A recent Cochrane Evidenced based
review/meta-analysis demonstrated that all antibiotic regimens had equivocal clinical success.
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Page G
Table 2. IDSA and Surgical Infection Society Guidelines
Antibiotic
Regimen
Single Therapy
Low Risk
Cefoxitin
High Risk
Imipenem/cilastatin or
Meropenem
Ertapenem
Combination
Therapies
a
b
c
Ticarcillin/clavulanate
Piperacillin/tazobactam
Aminoglycosidea + metronidazoleb
Aminoglycosidea +Metronidazoleb
Cefazolin or Cefuroxime + Metronidazole
Ciprofloxacina + Metronidazoleb
Ciprofloxacin, levofloxacin or moxifloxacinc +
Metronidazoleb
3rd or 4th gen Cephalosporin +
Metronidazoleb
Aminoglycoside = gentamicin, or tobramycin;
Clindamycin may be used as an alternative. There have been reports of increasing resistance of
B fragilis to clindamycin, cefoxitin and fluoroquinolones.
Fluoroquinolones have shown increasing resistance of E.coli and B. fragilis. Please review susceptibility
patterns prior to starting fluoroquinolones and follow up with culture & sensitivity reports.
Recommendations based on Antibiotics on Fraser Health Formulary
Based on the evidence of comparable efficacy, choice of antibiotic therapy should be dictated by local
antibiogram data, possible adverse effects, cost, preparation time and health care provider time. Of note,
there have been recent reports of increasing rates of B. fragilis resistance to clindamycin, cefotetan, cefoxitin
and fluoroquinolones. As well, there is increased rates of E.coli resistance to Fluoroquinolones. (contact your
local Pharmacy Department or Microbiology Department for the 2007 FHA Antibiograms.) In general, most
patients can be empirically started on a cephalosporin plus anti-anaerobic agent. In patients with a penicillin
allergy, an aminoglycoside plus anti-anaerobic agent can be used. Recommendations for the antibiotic
regimens available on the Fraser Health Formulary are listed in Table 3.
1) In low-risk patients with community-acquired intraabdominal infections, empirical coverage against
Enterococcus sp. and Pseudomonas sp. is not necessary.
2) In high-risk patients and in patients with anticipated prolonged hospital stay, extended coverage
against most Gm (-) aerobic/facultative anaerobic organisms is recommended. Several risk factors
associated with treatment failure and increased mortality have been identified in the literature.
These high-risk features include advanced age, poor nutritional status, a low serum albumin
concentration, pre-existing medical disorders such as significant cardiovascular disease, a higher
APACHE II score, and the presence of resistant microorganisms. These patients should have
extended coverage for Pseudomonas sp. Coverage for Enterococcusl sp. is not routinely
recommended, but should be considered in patients that are at higher risk of health care associated
infections or when guided by microbial culture results.
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Page H
Duration of Therapy
The optimal duration of therapy for intraabdominal infections remains controversial. In prospective,
randomized studies, the duration is usually determined at the discretion of the investigators and may range
from 3 to 14 days or longer if needed. Based on limited clinical data and expert opinion, the Surgical Infection
Society recommends treatment to be limited to no more than 5 to 7 days for most patients with complicated
intraabdominal infections. In general, antibiotics should be continued until the resolution of clinical signs of
infection, including normalization of temperature, WBC count and return of gastrointestinal function. If there is
persistent or recurrent evidence of infection after 5 to 7 days of therapy, then appropriate diagnostic
investigations should be undertaken.
Table 3. Antibiotic regimens for intraabdominal infections based on FHA Formulary availability
Low-risk patients
Antibiotic Regimen (average doses listed)a
Cefazolin 1 g IV Q8H
Or Cefuroxime 750 mg IV Q8H
Plus Metronidazole 500 mg IV Q8-12H
Gentamicin 2.5 mg/Kg mg IV Q8Ha
Plus Metronidazole 500 mg IV Q8-121H
Or Clindamycin 600 mg IV Q8H b
High-risk patients
(always consider
confounding factors
such as immune status,
sepsis, etc.)
Drug cost per day
$11.22
$8.85
$3.66
$8.31
$7.14
$3.66
Ertapenem 1g IV Q24H
$49.95
Ticarcillin/Clavulinate 3.1g IV Q6H
Cetriaxone 1 g IV Q24H
Plus Metronidazole 500 mg IV Q8-12H
$38.44
$34.00
$3.66
Gentamicin 2.5 mg/Kg mg IV Q8Ha
Plus Metronidazole 500 mg IV Q8-12H
Or Clindamycin 600 mg IV Q8H b
(+/- Ampicillin 1G IV Q6H)
$8.31
$7.14
$3.66
$3.00
Ciprofloxacin 400 mg IV Q12Hc
Plus Metronidazole 500 mg IV Q8-12H
$66.00
$3.66
Piperacillin/tazobactam 3.375 mg IV Q6H
$62.28
Imipenem/cilastatin or Meropenem
500 mg IV Q6H
$97.52
a
Average doses listed; may modify as appropriate to tailor to the needs of the patient. Consult local
clinical pharmacist for assistance
b There have been reports of increasing resistance of B fragilis to clindamycin, cefoxitin and
fluoroquinolones.
c There have been reports of increasing resistance of E. coli to fluoroquinolones. Local antibiogram
patterns should be reviewed prior to starting Fluoroquinolones, and culture and sensitivities should be
followed.
ACKNOWLEDGEMENT
Many thanks to Dr. Yasemin Arikan and members of the FHA Infectious Diseases Subcommittee for their
review and feedback.
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Page I
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